Understanding the Science of Resistance Training: An Evolutionary Perspective

Effect of aerobic training versus resistance training for improving cardiorespiratory fitness and body composition in middle-aged to older adults: A systematic review and meta-analysis of randomized controlled trials

This systematic review and meta-analysis aimed to examine the influence of aerobic training (AT) versus resistance training (RT) on cardiorespiratory fitness and body composition in middle-aged to older adults. Four electronic databases including PubMed, Scopus, Cochrane CENTRAL, and web of science, as well as reference lists of included randomized controlled trials (RCTs) were searched from inception to April 2024. Data were pooled by the inverse-variance method and reported as mean differences (MDs) with 95 % confidence intervals (CIs). Thirty-eight RCTs, with a pooled sample of 1682 participants, met our inclusion criteria. Meta-analysis revealed that AT significantly improved VO2max/peak (MD = 1.80, 95 % CI: 0.96 to 2.64, p < 0.0001) and 6-MWT (MD = 18.58, 95 % CI: 10.38 to 26.78, p < 0.00001), and significantly decreased body mass (MD = -1.23, 95 % CI: -1.98 to -0.47, p = 0.001) versus RT. However, changes in lean body mass favored RT over AT. Moreover, changes in VO2max/peak and 6-MWT following AT were significant among both healthy and unhealthy participants, or men and women, after medium-term (< 24 weeks) and long-term (≥ 24 weeks) interventions, and among participants aged ≤65 and >65. Our results propose that AT should be considered an efficient approach to improving cardiorespiratory fitness and overall body composition with aging, particularly in terms of VO2max and 6-MWT performance. However, for improvements in lean body mass, RT may be more beneficial. Therefore, a combination of AT and RT might be optimal for comprehensive fitness and body composition improvements with aging.

The Impact of Resistance Exercise Training on Glycemic Control Among Adults with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: The prevalence of type 2 diabetes mellitus (T2DM) presents a challenge for health organizations because of its high likelihood of morbidity and mortality. There is an increasing body of evidence exploring the efficacy of resistance training (RT) alone on glycemic control. Objective: To update the effectiveness of RT on glycosylated hemoglobin (HbA1c) and fasting glucose in adults diagnosed with T2DM. Methods: CINAHL (EBSDCO), PubMed, MEDLINE (Ovid), and EMBASE (Ovid) databases were searched from inception to 30 January 2024. Published randomized controlled trials (RCTs) of adult humans with T2DM assessing the impact of RT on HbA1c and fasting glucose compared with control condition were included. Data were pooled by the inverse-variance method and reported as mean differences (MDs) with 95% confidence intervals (CIs). Results: Forty-six RCTs totaling 2130 participants met the inclusion criteria. Meta-analysis demonstrated RT significantly reduced HbA1c (MD -0.50% [95% CI, -0.67, -0.34 %], p < .00,001) and fasting glucose (MD -12.03 mg/dl [95% CI, -19.36, -4.69 mg/dl], p = .001). Subgroup analyses found that exercise training durations, gender, and risk of bias had statistically significant effects on HbA1c levels and fasting glucose concentrations after resistance training. However, meta-regression analyses revealed that variables including year of publication, number of sessions per week, mean sample age, sample size, and study quality scores did not significantly affect the change in either HbA1c or glucose. Conclusion: Our meta-analysis with meta-regression delivers further evidence that RT programs are effective approach in attenuation of HbA1c and fasting glucose in individuals with T2DM.

Qualified fitness trainers practice scientifically based judgement in prescribing exercise programs

Fitness trainers are widely in demand by both commercial fitness centres and individual people. They serve members in one-to-one personal training (PT) or group training (GX) in commercial fitness centres. However, the services provided by fitness trainers have not been consistent across the industry. This service inconsistency has led to an increased doubt about professionalism in conducting safe and correct exercise for the public. No studies have evaluated how fitness trainers make decisions when they curate exercise programs for members. This research utilized a qualitative semi-structured interview method to collect data from 16 fitness trainers in Greater Kuala Lumpur, Malaysia. Inverview data was verbatim transcribed and analyzed using a theory-driven analysis. The study investigated fitness training professional decision-making processes when they design and precribe fitness execise programming to clients. Using Cognitive Continuum Theory (CCT) as a lens to explore the decision-making processes revealed a dichotomy of decision-making processes for curating personal training and group training. Feedback mechanism in the implementation of personal training was proven to be more personalized than group training. There are four themes in decision-making processed discovered to be impreative characteristics for fitness trainers. The application of CCT allowed further understanding of the implementation of exercise programs for PT and GX training when fitness trainers modified exercise programs.

Strength training as a non-pharmacological alternative to improve body composition, and quality of life in people with spinal cord injury: A systematic review

INTRODUCTION

Spinal cord injuries (SCI) have physiological, emotional, and economic consequences in the lives of affected people. Resistance training (RT) is efficient in improving several physiological factors, quality of life, and body composition. Due to the scarce literature on the analysis of isolated RT, the objective of this systematic review is to evaluate the effects of RT without the association of other techniques, in aspects related to the quality of life and body composition of people with SCI.

EVIDENCE ACQUISITION

The research was carried out in databases such as Pubmed, Cochrane, and Web of Science using the terms ("Spinal cord injury") AND (("Resistance Training") OR ("Strength training")). Given the lack of evidence on the subject, no deadline was set for the study to be eligible for analysis.

EVIDENCE SYNTHESIS

The search for the articles was carried out in November of 2023 and returned 470 results, of which 315 remained after the elimination of duplicates, with 281 being excluded after title analysis. A total of 34 abstracts were analyzed and 29 studies were excluded, leaving 5 complete articles for thorough analysis.

CONCLUSIONS

After analyzing the main results, we concluded that RT promotes significant improvements in body composition, pain, stress and depression symptoms, increased functionality, physical awareness, and quality of life.

Dose-Response Modelling of Resistance Exercise Across Outcome Domains in Strength and Conditioning: A Meta-analysis

BACKGROUND

Resistance exercise is the most common training modality included within strength and conditioning (S&C) practice. Understanding dose-response relationships between resistance training and a range of outcomes relevant to physical and sporting performance is of primary importance for quality S&C prescription.

OBJECTIVES

The aim of this meta-analysis was to use contemporary modelling techniques to investigate resistance-only and resistance-dominant training interventions, and explore relationships between training variables (frequency, volume, intensity), participant characteristics (training status, sex), and improvements across a range of outcome domains including maximum strength, power, vertical jump, change of direction, and sprinting performance.

METHODS

Data were obtained from a database of training studies conducted between 1962 and 2018, which comprised healthy trained or untrained adults engaged in resistance-only or resistance-dominant interventions. Studies were not required to include a control group. Standardized mean difference effect sizes were calculated and interventions categorized according to a range of training variables describing frequency (number of sessions per week), volume (number of sets and repetitions performed), overall intensity (intensity of effort and load, categorised as low, medium or high), and intensity of load (represented as % of one-repetition maximum [1RM] prescribed). Contemporary modelling techniques including Bayesian mixed-effects meta-analytic models were fitted to investigate linear and non-linear dose-responses with models compared based on predictive accuracy.

RESULTS

Data from a total of 295 studies comprising 535 groups and 6,710 participants were included with analyses conducted on time points ≤ 26 weeks. The best performing model included: duration from baseline, average number of sets, and the main and interaction effects between outcome domain and intensity of load (% 1RM) expressed non-linearly. Model performance was not improved by the inclusion of participant training status or sex.

CONCLUSIONS

The current meta-analysis represents the most comprehensive investigation of dose-response relationships across a range of outcome domains commonly targeted within strength and conditioning to date. Results demonstrate the magnitude of improvements is predominantly influenced by training intensity of load and the outcome measured. When considering the effects of intensity as a % 1RM, profiles differ across outcome domains with maximum strength likely to be maximised with the heaviest loads, vertical jump performance likely to be maximised with relatively light loads (~ 30% 1RM), and power likely to be maximised with low to moderate loads (40-70% 1RM).

The influence of resistance exercise and aerobic exercise on type 2 diabetes: a meta-analysis

INTRODUCTION

Diabetes is a worldwide chronic disease. The incidence rate of this disease is high, and it is a common disease in clinics. At present, the incidence rate of diabetes patients is increasing year by year due to the increasing work pressure, the accelerated pace of life, the change of diet, the reduction of labor, and the acceleration of aging.

EVIDENCE ACQUISITION

The computer retrieves four databases to obtain random controlled trials on the influence of resistance exercise and aerobic exercise on type 2 diabetes. After a rigorous literature quality evaluation, data analysis was performed using RevMan 5.3 software.

EVIDENCE SYNTHESIS

Ten studies were ultimately included in this meta-analysis. 10 studies reported the HbA1c of the test group and the control group, which was no significant statistical significance (SMD: -0.01; 95% CI: -0.20,0.19; P=0.959) than the control group, HOMA-IR (SMD: 0.02; 95% CI: -0.65,0.69; P=0.954), SBP (SMD: 3.92; 95% CI: -0.92,8.75; P=0.112), DBP (SMD: 0.67; 95% CI: -3.66,5.01; P=0.761), HDL (SMD: -0.08; 95% CI: -2.79,2.64; P=0.955), TG (SMD: -7.51; 95% CI: -21.25,6.22; P=0.284) and TC (SMD: 9.10; 95% CI: -13.43,31.62; P=0.428).

CONCLUSIONS

The results of this study suggest that both resistance exercise and aerobic exercise may be effective on patients with type 2 diabetes, as evidenced by HbA1c, HOMA-IR, SBP, DBP, HDL, TG and TC. There is no significant difference in their impact on type 2 diabetes patients, and the above conclusions need to be verified by more high-quality studies.

Physiological Mechanisms That Impact Exercise Adaptations for Individuals With Down Syndrome

ABSTRACT

Post, EM, and Kraemer, WJ. Physiological mechanisms that impact exercise adaptations for individuals with Down syndrome. J Strength Cond Res 37(12): e646-e655, 2023-Down syndrome (DS) is the most common chromosomal disorder diagnosed in the United States since 2014. There is a wide range of intellectual severities, with the average IQ of individuals with DS at approximately 50 and adults without intellectual delay at approximately 70-130. Individuals with DS vary from mild to severe cognitive impairment, depending on the phenotypic penetration on the 21st chromosome, with the average cognitive capacity equivalent to a cognitive functioning of an 8- to 9-year-old child. To have successful health, all aspects of health must be considered (i.e., overall health, fitness, and social). Both aerobic training and resistance training (RT) are favored for a healthy lifestyle. Resistance training specifically can help improve motor function and overall activities of daily living. Although many motivational and environmental barriers for individuals with DS can make exercising difficult, there are many ways to overcome those barriers (both intrinsically and extrinsically). Individuals with DS should strive for 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic exercise a week or a combination of both. The individual should also strive for 2 or more days a week of strengthening activities, such as RT, involving all muscle groups. These activities will help improve many aspects of life, leading to a better quality of life. Regular group exercise activity can help increase self-confidence and success socially in life. This review will focus on the underlying biological mechanisms related to DS, their influence on exercise, and the roles exercise plays in mediating positive health, physical fitness, and social lifestyle outcomes.

Mechanisms of mechanical overload-induced skeletal muscle hypertrophy: current understanding and future directions

Mechanisms underlying mechanical overload-induced skeletal muscle hypertrophy have been extensively researched since the landmark report by Morpurgo (1897) of "work-induced hypertrophy" in dogs that were treadmill trained. Much of the preclinical rodent and human resistance training research to date supports that involved mechanisms include enhanced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, an expansion in translational capacity through ribosome biogenesis, increased satellite cell abundance and myonuclear accretion, and postexercise elevations in muscle protein synthesis rates. However, several lines of past and emerging evidence suggest that additional mechanisms that feed into or are independent of these processes are also involved. This review first provides a historical account of how mechanistic research into skeletal muscle hypertrophy has progressed. A comprehensive list of mechanisms associated with skeletal muscle hypertrophy is then outlined, and areas of disagreement involving these mechanisms are presented. Finally, future research directions involving many of the discussed mechanisms are proposed.

The Effects of Strength and Conditioning Interventions on Sprinting Performance in Team Sport Athletes: A Systematic Review and Meta-Analysis

Murphy, A, Burgess, K, Hall, AJ, Aspe, RR, and Swinton, PA. The effects of strength and conditioning interventions on sprinting performance in team sport athletes: a systematic review and meta-analysis. J Strength Cond Res 37(8): 1692–1702, 2023—Linear sprinting is a key determinant of athletic performance within team sports. The aims of the review were to quantify and compare the effectiveness of popular strength and conditioning (S&C) training modes to improve sprint performance in team sport athletes, with additional focus on potential moderators and the relationships between improvements in physical factors (e.g., strength, power, and jump performance) and improvements in sprint performance. Inclusion was restricted to resistance, plyometric, sprint, and combined training interventions comprising team sport athletes. Multilevel, Bayesian’s meta-analysis and meta-regression models conducted with standardized mean difference effect sizes were used to investigate training modes and potential moderators. Weighted regression models conducted on shrunken estimates from initial Bayesian’s meta-analyses were used to quantify relationships between improvements in physical factors and sprint performance. Certainty of evidence was assessed using the grading of recommendations assessment development and evaluation (GRADE) approach. Similar improvements in sprint performance were obtained across training modes, with some evidence of the largest effects with resistance training ( = 0.55 [95% credible interval [CrI]: 0.36–0.78; very low certainty]). A strong moderating effect of training intensity was identified across all training modes with evidence of greater improvements in sprint performance with high-intensity training ( = 0.17 [95% CrI: 0.01–0.33; very low certainty]). Strong positive relationships were identified between improvements in all physical factors and sprint performance ( = 0.56 [95% CrI: 0.36–0.77; low certainty], = 0.80 [95% CrI: 0.50–1.0; low certainty], = 0.78 [95% CrI: 0.57–0.97; low certainty]). The findings indicate that focus on developing speed in team sport athletes should be placed on S&C training with high intensities, including the use of resisted sprint training.

Effects of submaximal and supramaximal accentuated eccentric loading on mass and function

Introduction: Eccentric-overload (EO) resistance training emerges as an alternative to more optimally prescribe intensity relative to the force generation capabilities of the eccentric muscle contraction. Given the difficulties to individually prescribe absolute eccentric loads relative to each person's eccentric ability, setting the load relative to the concentric one-repetition maximum (1-RM) is the most used EO training approach. Therefore, we investigated the effects of submaximal and supramaximal (i.e., eccentric loads above 100% of 1-RM) accentuated eccentric training on changes in lean mass, anabolic hormonal responses and muscle function. Methods: Physically active university students (n = 27) were randomly assigned to two training groups. Participants in the training groups performed dominant leg isotonic training twice a week for 10 weeks (four sets of eight repetitions). Isotonic resistance was generated by an electric-motor device at two different percentages of 1-RM for the eccentric phase; 90% submaximal load, SUB group) and 120% (supramaximal load, SUPRA group). Concentric load was the same for both groups (30% of 1-RM). Changes in total thigh lean mass (TTLM), anabolic hormonal responses (growth hormone, IGF-1, IL-6, and total testosterone), unilateral leg-press 1-RM, maximal voluntary isometric contractions (MVIC), local muscle endurance (XRM), muscle power at 40 (PP40), 60 (PP60) and 80% (PP80) of the 1-RM, and unilateral vertical jump height before and after training were compared between groups. Results: After training, both SUB and SUPRA groups showed similar increases (p < 0.05) in MVIC (19.2% and 19.6%), XRM (53.8% and 23.8%), PP40 (16.2% and 15.7%), TTLM (2.5% and 4.2%), IGF-1 (10.0% and 14.1%) and IL-6 (58.6% and 28.6%). However, increases in 1-RM strength (16.3%) and unilateral vertical jump height (10.0%-13.4%) were observed for SUPRA only. Indeed, SUPRA was shown to be more favorable than SUB training for increasing 1-RM [ES = 0.77 (1.49-0.05)]. Unilateral muscle power at medium and high intensity (10.2% and 10.5%) also increased in SUB but without significant differences between groups. Discussion: Similar functional and structural effects were demonstrated after 10 weeks EO training with submaximal and supramaximal eccentric loads. Although supramaximal loading might be superior for increasing 1-RM, the use of this approach does not appear to be necessary in healthy, active individuals.

The effect of blood flow restriction training combined with electrical muscle stimulation on neuromuscular adaptation: a randomized controlled trial

Objective: Low-intensity resistance training (≤25% 1RM) combined with blood flow restriction training (BFRT) is beneficial to increasing muscle mass and muscle strength, but it cannot produce increased muscle activation and neuromuscular adaptation, as traditional high-intensity strength training does. The purpose of this study is to investigate the effects of independently applying BFRT and electrical muscle stimulation (EMS), as well as combining the two methods, on muscle function. Methods: Forty healthy participants with irregular exercise experiences were randomly assigned to four groups: BFRT-alone group (BFRT, n = 10), EMS-alone group (EMS, n = 10), BFRT combined with EMS group (CMB, n = 10), and the control group (CTR, n = 10). All participants received low-intensity squat training at a load of 25% 1RM 5 times/week for 6 weeks. Cross-sectional area (CSA) and electromyographic root mean square (RMS) in the rectus femoris, as well as peak torque (PT) of the knee extensor, were measured before and following a 6-week intervention. Results: Following the 6-week intervention, the increases in muscle activation in the CMB group were statistically higher than those in the BFRT group (p < 0.001), but not different from those in the EMS group (p = 0.986). Conclusion: These data suggest that the combination of BFRT and EMS for low-intensity squat training improved the muscle strength of the lower limbs by promoting muscle hypertrophy and improving muscle activation, likely because such a combination compensates for the limitations and deficiencies of the two intervention methods when applied alone.

Interpreting magnitude of change in strength and conditioning: Effect size selection, threshold values and Bayesian updating

The magnitude of change following strength and conditioning (S&C) training can be evaluated comparing effect sizes to thresholds. This study conducted a series of meta-analyses and compiled results to identify thresholds specific to S&C, and create prior distributions for Bayesian updating. Pre- and post-training data from S&C interventions were translated into standardised mean difference (SMD_pre) and percentage improvement (%Improve) effect sizes. Bayesian hierarchical meta-analysis models were conducted to compare effect sizes, develop prior distributions, and estimate 0.25-, 0.5-, and 0.75-quantiles to determine small, medium, and large thresholds, respectively. Data from 643 studies comprising 6574 effect sizes were included in the analyses. Large differences in distributions for both SMD_pre and %Improve were identified across outcome domains (strength, power, jump and sprint performance), with analyses of the tails of the distributions indicating potential large overestimations of SMD_pre values. Future evaluations of S&C training will be improved using Bayesian approaches featuring the information and priors developed in this study. To facilitate an uptake of Bayesian methods within S&C, an easily accessible tool employing intuitive Bayesian updating was created. It is recommended that the tool and specific thresholds be used instead of isolated effect size calculations and Cohen's generic values when evaluating S&C training.

Effects of moderate-intensity resistance exercise on blood glucose and pregnancy outcome in patients with gestational diabetes mellitus: A randomized controlled trial

OBJECTIVES

To investigate the effects of a structured moderate-intensity resistance exercise program on blood glucose levels and other health-related indicators in patients with GDM.

METHODS

A total of 99 patients with GDM in a tertiary class A general hospital were randomly divided into an experimental group and a control group. GDM patients in the control group received routine prenatal care, online education, and a personalized diabetes diet intervention. The experimental group was treated in the same way as the control group with the addition of a moderate intensity resistance exercise program.

RESULTS

The blood glucose levels in both groups were lower after the intervention compared with before intervention (P < 0.05). After intervention, the average fasting blood glucose, the 2 h postprandial blood glucose, the utilization rate of insulin, the amount of insulin, gestational weight gain and blood pressure (P < 0.05) in the experimental group were lower than the control group. In addition, there was no statistical significance in the incidence of adverse pregnancy outcomes between the two groups after intervention (P > 0.05).

CONCLUSIONS

Moderate intensity resistance exercise was helpful for improvement of blood glucose control and insulin use, gestational weight gain and blood pressure in patients with GDM. In the future, long-term follow-up of both maternal and newborn infants should be performed to assess the long-term effects of exercise intervention on maternal and child health. The impact on the risk of obesity and diabetes may need to be further clarified. The trial was approved by the registration of the Chinese Clinical Trial Registry, and registration number: ChiCTR1900027929.

Effects of resistance exercise on blood glucose level and pregnancy outcome in patients with gestational diabetes mellitus: a randomized controlled trial

INTRODUCTION

To date, the effects of resistance exercise on diabetes-related parameters (blood glucose level and insulin use) and pregnancy outcome in participants with gestational diabetes mellitus (GDM) have not been compared with those of aerobic exercise. To investigate the effect of resistance exercise versus aerobic exercise on blood glucose level, insulin utilization rate, and pregnancy outcome in patients with GDM.

RESEARCH DESIGN AND METHODS

From December 2019 to December 2020, 100 pregnant women with GDM were selected and divided into a resistance exercise group (49 patients) and an aerobic exercise group (51 patients) randomly. The aerobic exercise group received an aerobic exercise intervention, while the resistance exercise group received a resistance exercise intervention. Both groups received exercise intervention for 50-60 min, 3 times per week, lasting for 6 weeks. In addition, patients in both groups received the same routine care, including personalized dietary intervention, online education, and school courses for pregnant women.

RESULTS

The blood glucose level in the resistance exercise group and the aerobic exercise group was lower after the intervention than before the intervention (p<0.05). After the intervention, no significant differences were observed in the fasting blood glucose level, insulin utilization rate, and incidence of adverse pregnancy outcomes between the two groups (p>0.05); however, significant differences were noted in 2-hour postprandial blood glucose level and exercise compliance between the two groups (p<0.05), with the resistance exercise group showing better outcomes than the aerobic exercise group.

CONCLUSIONS

Resistance exercise is more compliant for pregnant women with GDM than aerobic exercise; hence, it is necessary to popularize resistance exercise in this specific population group. Long-term effects of resistance exercise should be evaluated in future studies.

TRIAL REGISTRATION NUMBER

ChiCTR 1900027929.

Velocity-Based Resistance Training on 1-RM, Jump and Sprint Performance: A Systematic Review of Clinical Trials

Weight resistance training (RT) has been shown to positively influence physical performance. Within the last two decades, a methodology based on monitoring RT through movement velocity (also called velocity-based resistance training, VBRT) has emerged. The aim of this PRISMA-based systematic review was to evaluate the effect of VBRT programs on variables related to muscle strength (one-repetition maximum, 1-RM), and high-speed actions (vertical jump, and sprint performance) in trained subjects. The search for published articles was performed in PubMed/MEDLINE, SPORT Discus/EBSCO, OVID, Web of Science, Scopus, and EMBASE databases using Boolean algorithms independently. A total of 22 studies met the inclusion criteria of this systematic review (a low-to-moderate overall risk of bias of the analyzed studies was detected). VBRT is an effective method to improve 1-RM, vertical jump and sprint. According to the results of the analyzed studies, it is not necessary to reach high muscle failure in order to achieve the best training results. These findings reinforce the fact that it is possible to optimize exercise adaptations with less fatigue. Future studies should corroborate these findings in female population.

Training-Induced Muscle Adaptations During Competitive Preparation in Elite Female Rowers

Training-induced adaptations in muscle morphology, including their magnitude and individual variation, remain relatively unknown in elite athletes. We reported changes in rowing performance and muscle morphology during the general and competitive preparation phases in elite rowers. Nineteen female rowers completed 8 weeks of general preparation, including concurrent endurance and high-load resistance training (HLRT). Seven rowers were monitored during a subsequent 16 weeks of competitive preparation, including concurrent endurance and resistance training with additional plyometric loading (APL). Vastus lateralis muscle volume, physiological cross-sectional area (PCSA), fascicle length, and pennation angle were measured using 3D ultrasonography. Rowing ergometer power output was measured as mean power in the final 4 minutes of an incremental test. Rowing ergometer power output improved during general preparation [+2 ± 2%, effect size (ES) = 0.22, P = 0.004], while fascicle length decreased (−5 ± 8%, ES = −0.47, P = 0.020). Rowing power output further improved during competitive preparation (+5 ± 3%, ES = 0.52, P = 0.010). Here, morphological adaptations were not significant, but demonstrated large ESs for fascicle length (+13 ± 19%, ES = 0.93), medium for pennation angle (−9 ± 15%, ES = −0.71), and small for muscle volume (+8 ± 13%, ES = 0.32). Importantly, rowers showed large individual differences in their training-induced muscle adaptations. In conclusion, vastus lateralis muscles of elite female athletes are highly adaptive to specific training stimuli, and adaptations largely differ between individual athletes. Therefore, coaches are encouraged to closely monitor their athletes' individual (muscle) adaptations to better evaluate the effectiveness of their training programs and finetune them to the athlete's individual needs.

Effects of velocity based training vs. traditional 1RM percentage-based training on improving strength, jump, linear sprint and change of direction speed performance: A Systematic review with meta-analysis

Background

There has been a surge of interest on velocity-based training (VBT) in recent years. However, it remains unclear whether VBT is more effective in improving strength, jump, linear sprint and change of direction speed (CODs) than the traditional 1RM percentage-based training (PBT).

Objectives

To compare the training effects in VBT vs. PBT upon strength, jump, linear sprint and CODs performance.

Data sources

Web of science, PubMed and China National Knowledge Infrastructure (CNKI).

Study eligibility criteria

The qualified studies for inclusion in the meta-analysis must have included a resistance training intervention that compared the effects of VBT and PBT on at least one measure of strength, jump, linear sprint and CODs with participants aged ≥16 yrs. and be written in English or Chinese.

Methods

The modified Pedro Scale was used to assess the risk of bias. Random-effects model was used to calculate the effects via the mean change and pre-SD (standard deviation). Mean difference (MD) or Standardized mean difference (SMD) was presented correspondently with 95% confidence interval (CI).

Results

Six studies met the inclusion criteria including a total of 124 participants aged 16 to 30 yrs. The differences of training effects between VBT and PBT were not significant in back squat 1RM (MD = 3.03kg; 95%CI: -3.55, 9.61; I² = 0%) and load velocity 60%1RM (MD = 0.02m/s; 95%CI: -0.01,0.06; I² = 0%), jump (SMD = 0.27; 95%CI: -0.15,0.7; I² = 0%), linear sprint (MD = 0.01s; 95%CI: -0.06, 0.07; I² = 0%), and CODs (SMD = 0.49; 95%CI: -0.14, 1.07; I² = 0%).

Conclusion

Both VBT and PBT can enhance strength, jump, linear sprint and CODs performance effectively without significant group difference.

Effects of Resistance Training Performed with Different Loads in Untrained and Trained Male Adult Individuals on Maximal Strength and Muscle Hypertrophy: A Systematic Review

The load in resistance training is considered to be a critical variable for neuromuscular adaptations. Therefore, it is important to assess the effects of applying different loads on the development of maximal strength and muscular hypertrophy. The aim of this study was to systematically review the literature and compare the effects of resistance training that was performed with low loads versus moderate and high loads in untrained and trained healthy adult males on the development of maximal strength and muscle hypertrophy during randomized experimental designs. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (2021) were followed with the eligibility criteria defined according to participants, interventions, comparators, outcomes, and study design (PICOS): (P) healthy males between 18 and 40 years old, (I) interventions performed with low loads, (C) interventions performed with moderate or high loads, (O) development of maximal strength and muscle hypertrophy, and (S) randomized experimental studies with between- or within-subject parallel designs. The literature search strategy was performed in three electronic databases (Embase, PubMed, and Web of Science) on 22 August 2021. Results: Twenty-three studies with a total of 563 participants (80.6% untrained and 19.4% trained) were selected. The studies included both relative and absolute loads. All studies were classified as being moderate-to-high methodological quality, although only two studies had a score higher than six points. The main findings indicated that the load magnitude that was used during resistance training influenced the dynamic strength and isometric strength gains. In general, comparisons between the groups (i.e., low, moderate, and high loads) showed higher gains in 1RM and maximal voluntary isometric contraction when moderate and high loads were used. In contrast, regarding muscle hypertrophy, most studies showed that when resistance training was performed to muscle failure, the load used had less influence on muscle hypertrophy. The current literature shows that gains in maximal strength are more pronounced with high and moderate loads compared to low loads in healthy adult male populations. However, for muscle hypertrophy, studies indicate that a wide spectrum of loads (i.e., 30 to 90% 1RM) may be used for healthy adult male populations.

Content Analysis of Patent Applications for Strength Training Equipment Filed in the United States Before 1980

ABSTRACT

Nuzzo, JL. Content analysis of patent applications for strength training equipment filed in the United States before 1980. J Strength Cond Res 35(10): 2952-2962, 2021-Strength training history is an emerging academic area. The aim of the current study was to describe quantitively the history of inventions for strength training equipment. Content analysis was conducted of patent applications for strength training equipment filed with the U.S. Patent and Trademark Office before 1980. Applications were identified using relevant keyword searches in Google Patents. A total of 551 patent applications were analyzed. The earliest application identified was filed in 1860. Applications never exceed 6 per year until 1961 after which applications increased substantially, with a peak of 54 in 1979. Men invented 98.7% of all strength training devices. Lloyd J. Lambert, Jr. was the most prolific inventor, with 10 inventions. Types of inventions included mobile units (34.5%), stationary machines (27.9%), dumbbells (16%), racks or benches (8.0%), barbells (6.7%), and Indian clubs (3.8%). Common features included seats or benches (18.7%), cable-pulley systems (15.1%), weight stacks (8.2%), weight trays (4.5%), and cams (2.2%). Common types of resistance included weights or plates (33.2%), springs (11.6%), friction (9.1%), elastic bands (5.3%), and hydraulic (3.8%). Proposed invention benefits included adjustable resistance (37.4%), inexpensive (36.1%), simple to use (32.8%), compact design or easy storage (27.0%), multiple exercise options (26.1%), safety and comfort (25.4%), effectiveness (23.6%), portability (20.5%), adjustable size (15.8%), sturdiness or durability (15.8%), home use (13.6%), and light weight (13.6%). Certain aspects of strength training equipment have evolved over time. However, overall purposes and benefits of inventions have remained constant (e.g., affordability, convenience, personalization, safety, and effectiveness).

History of Strength Training Research in Man: An Inventory and Quantitative Overview of Studies Published in English Between 1894 and 1979

ABSTRACT

Nuzzo, JL. History of strength training research in man: an inventory and quantitative overview of studies published in English between 1894 and 1979. J Strength Cond Res 35(5): 1425-1448, 2021-Limited scholarship exists on the history of strength training research. The current review advances existing qualitative and biographical work by inventorying all experimental studies and case reports published before 1980 on the effects of ≥1 week of strength training on human health and function. Data on authors, journals, citations, study samples, training interventions, study outcomes, and study themes were extracted and summarized. Three hundred thirty-nine strength training studies were published between 1894 and 1979. Studies included 14,575 subjects, with 10,350 undergoing strength training. Subjects were usually healthy (81.1% of articles), university students (51.0%), or aged 18-65 years (86.7%). Men comprised 70.0% of subjects. Interventions typically involved isoinertial only (64.6%) or isometric only (35.4%) training. Upper-body interventions were more common (35.4%) than lower-body interventions (27.4%). Duration and frequency of training were typically 4-8 weeks (55.3%) and 3 days per week (39.2%), respectively. Isometric maximal voluntary contractions (54.0%) and one repetition maximum (20.4%) were the most common muscle strength tests. Other common outcomes included limb girths (20.9%) and muscle endurance (19.5%). Common research themes were physiology (54.3%), physical fitness (28.9%), and injury/rehabilitation (20.4%). The 339 studies have been cited 21,996 times. Moritani and deVries' 1979 article on time course of neuromuscular adaptations is the most highly cited (1,815 citations). DeLorme (5 articles and 772 citations), Hellebrandt (4 articles and 402 citations), Rasch (9 articles and 318 citations), and Berger (12 articles and 1,293 citations) made the largest contributions. Research Quarterly published the most articles (27.4%). The history of strength training research is discussed in the context of the results.

Effects of Blood Flow Restriction Training on Muscle Strength and Pain in Patients With Knee Injuries: A Meta-Analysis

BACKGROUND

Due to the pain caused by knee injuries, low-load resistance training with blood flow restriction (L-BFR) may be a potential adjuvant therapeutic tool in the rehabilitation of knee injuries. This review aimed to analyze the effectiveness of L-BFR training modality in knee rehabilitation.

DESIGN

A meta-analysis was conducted to determine the potential impact of blood flow restriction on patients with knee injuries. PubMed, EBSCO, and Web of Science databases were searched for eligible studies from January 2000 until January 2020. The mean differences of the data were analyzed using Revman 5.3 software with a 95% confidence interval.

RESULTS

Nine studies fulfilled the inclusion criteria. These studies involved 179 patients who received L-BFR, 96 patients who underwent high-load resistance training, and another 94 patients who underwent low-load resistance training. The analysis of pooled data showed that patients in both the L-BFR (standardized mean difference, 0.83 [0.53, 1.14], P < 0.01) and high-load resistance training (standardized mean difference, -0.09 [-0.43, 0.24], P = 0.58) groups experienced an increase in muscle strength after the training. In addition, pain score was significantly reduced in the L-BFR group compared with the other two groups (standardized mean difference, -0.61 [-1.19, -0.03], P = 0.04).

CONCLUSIONS

Muscle strength increased after L-BFR and high-load resistance training compared with low-load resistance training. Furthermore, pain score was significantly reduced after L-BFR. Hence, L-BFR is a potential intervention to be applied in rehabilitation of knee injuries.

Dissimilar perceptual response between trained women and men in resistance training to concentric failure: A quasi-experimental study

PURPOSE

This study compared sex-related affective responses during resistance training performed to concentric failure.

METHODS

The study was a non-randomized trial (quasi-experimental study). Well-trained young participants were allocated into two groups according to sex (Women, n = 7, 21.1 ± 6.0 years, 57.6 ± 5.0 kg; and Men, n = 7, 28.3 ± 5.7 years, 88.3 ± 11.4 kg). Participants visited the laboratory three times: 1) 12-repetition maximum; 2-3) resistance training to concentric failure sessions. Perceptual measures were assessed before, during, and immediately after the resistance training sessions. The following were assessed: a) rating of perceived exertion for effort (RPE-E) and discomfort (RPE-D), b) feeling scale, c) physical activity affect scale (PAAS), d) felt arousal scale, and e) physical activity enjoyment scale (PACES).

RESULTS

High levels of RPE-E and RPE-D were reported without between-groups differences (p > 0.218). Women reported a reduction in the feeling scale (p = 0.001) whereas men did not (p > 0.680). Larger effect sizes were observed for women compared to men in the felt arousal scale and PAAS (negative affect and fatigue). Feeling scale and felt arousal scale data plotted in a circumplex model of affect indicated a transition to high-activation and unpleasant-affect only for the women. There was good reliability between results from sessions 1 and 2.

CONCLUSIONS

Training to concentric failure resulted in negative changes in affective perceptual responses only for women. This type of training should be used with caution since it may change the affect perception and reduce training adherence in women. Further studies are needed using larger sample sizes, different resistance-training exercises, and diverse training methods.

Effects of serious games in strength and functionality of patients with ulnar nerve lesion: two single-case reports

The objective of this study was to investigate the effect of serious games on hand muscle strength and functionality in a series of cases with ulnar nerve damage. Two patients were included in this 16-week intervention study using biofeedback. Electromyography electrodes and dynamometers were used in treatment. Functionality was assessed by Rosen and Lundborg score, Disabilities of the arm, shoulder and hand (DASH) questionnaire and International Classification of Functioning, Disability and Health (ICF). Grip and pinch strength were assessed by dynamometers. Results revealed an increase in sensory domain of Rosen and Lundborg score of the two patients. Patients increased values from the DASH questionnaire; however, they got better results with ICF. Grip strength of the two patients increased; pinch strength varied between patients; key pinch had the best results. Serious games can be effective to enhance hand strength and improve functionality in patients with ulnar nerve damage.

Photobiomodulation Therapy Effects on Resistance Training Volume and Discomfort in Well-Trained Adults: A Randomized, Double-Blind, Placebo-Controlled Trial

Objective: To investigate the effects of photobiomodulation therapy (PBMT) on resistance training volume and discomfort of well-trained adults. Background: PBMT has been used to attenuate fatigue in several physical exercise topics. However, it is unclear if PBMT can increase volume and reduce discomfort in resistance training well-trained individuals. Methods: Fourteen participants (women = 7, 27.7 ± 6.0 years and men = 7, 28.3 ± 5.7 years) visited the laboratory three times, 7 days apart. In the first visit, 12-repetition maximum (12-RM) test was performed unilaterally on the standing calf raise machine. In the second and third visits, subjects were randomly submitted to a PBMT (60 J per site, 6 sites per limb, total dose = 360 J) or placebo treatment on the gastrocnemius and soleus muscles with a randomized crossover design. Five minutes after the treatment, subjects began the resistance training session, performed unilaterally with six sets of repetitions to concentric failure. In addition, the rate of perceived exertion for discomfort (RPE-D) was asked after each set. Results: After the training session, it was observed a similar force reduction of 10.0 ± 13.6% for placebo and 7.7 ± 7.3% for PBMT (p = 0.815). No differences between PBMT and placebo was observed for the repetitions fatigue index (53.4 ± 11.7% and 50.0 ± 11.6%; p = 0.325) and total repetitions volume (55.4 ± 10.9 and 54.8 ± 13.0 reps; p = 0.764), respectively. RPE-D presented large means for all sets representing a large discomfort during resistance training to concentric failure for both PBMT (7.3 ± 2.3) and placebo (7.5 ± 2.5). Conclusions: The PBMT was not effective for increasing volume and reducing discomfort during resistance training performed to concentric failure by well-trained men and women.

Effects of 8 weeks of moderate-intensity resistance training on muscle changes in postmenopausal women with different angiotensin-converting enzyme insertion/deletion polymorphisms of interest

OBJECTIVE

The aim of the study was to explore the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and muscle adaptations to moderate-intensity resistance training in postmenopausal women.

METHODS

Forty healthy postmenopausal Chinese women (aged 53-66 years) were recruited and grouped by ACE I/D polymorphism (the homozygous deletion genotype [DD], n = 12; the I allele carriers [II/ID], n = 28). All participants performed an 8-week full-body resistance training program at moderate intensity with 15-repetition maximum. Upper- and lower-limb muscle mass, grip and back strength, anatomical cross-sectional area of the rectus femoris (ACSARF), isokinetic knee extension strength (MVCKE) and knee flexion strength were measured before and after training.

RESULTS

Our results showed significant genotype × time interaction in ACSARF and MVCKE (P = 0.007 and P = 0.03, respectively) with the DD group having greater changes in corresponding parameters than the I-allele carriers (P = 0.012 and P = 0.018, respectively). Multivariate linear regression results showed that the ACE DD genotype was positively related to the grip strength adaptation (r = 0.48, P = 0.05).

CONCLUSIONS

This study improves our understanding of the association between the ACE I/D polymorphism and muscular responses to moderate intensity resistance training among postmenopausal women and revealed that the DD genotype has predominant adaptations in grip strength, rectus femoris size, and knee extensor strength.

Evidence of Rehabilitative Impact of Progressive Resistance Training (PRT) Programs in Parkinson Disease: An Umbrella Review

Parkinson disease (PD) is a chronic neurodegenerative condition that leads to progressive disability. PD-related reductions in muscle strength have been reported to be associated with lower functional performance and balance confidence with an increased risk of falls. Progressive resistance training (PRT) improves strength, balance, and functional abilities. This umbrella review examines the efficacy of PRT regarding muscular strength in PD patients. The PubMed, PEDro, Scopus, and Cochrane Library databases were searched from January 2009 to August 2019 for systematic reviews and meta-analyses conducted in English. The populations included had diagnoses of PD and consisted of males and females aged >18 years old. Outcomes measured were muscle strength and enhanced physical function. Eight papers (six systematic reviews and meta-analyses and two systematic reviews) were considered relevant for qualitative analysis. In six of the eight studies, the reported severity of PD was mild to moderate. Each study analyzed how PRT elicited positive effects on muscle strength in PD patients, suggesting 10 weeks on average of progressive resistance exercises for the upper and lower limbs two to three times per week. However, none of the studies considered the postworkout follow-up, and there was no detailed evidence about the value of PRT in preventing falls. The possibility of PRT exercises being effective for increasing muscle strength in patients with PD, but without comorbidities or severe disability, is discussed. Overall, this review suggests that PRT should be included in rehabilitation programs for PD patients, in combination with balance training for postural control and other types of exercise, in order to preserve cardiorespiratory fitness and improve endurance in daily life activities.

Skeletal Muscle Aging Atrophy: Assessment and Exercise-Based Treatment

In the ordinary course of aging, individuals change their body composition, mainly reducing their skeletal muscle mass and increasing their fat mass. In association, muscle strength and functionality also decrease. The geriatric assessment allows knowing the baseline situation of the patients, determines the impact of diseases, and defines specific treatments. There are various tools to evaluate the health condition of older people. These tools include the assessment scales of necessary Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL), physical and functional assessment scales, and instruments that assess the cognitive state of the person. There are several strategies that have been proposed to combat skeletal muscle atrophy due to aging, such as physical exercise, nutritional supplements, or drugs. Some researchers have highlighted the efficacy of the combination of the mentioned strategies. In this chapter, we will focus only on physical exercise as a strategy to reduce skeletal muscle loss during aging.

The effects of exercise order during resistance training on muscular strength

The objective of this study was to compare the muscular strength adaptation during resistance training performed through two methods of exercise order. Thirty recreationally active, resistance untrained men were recruited as research participants and were divided into three groups based on their specific tasks to be performed during six weeks training intervention; i) order A (multi-joint followed by single-joint exercises) ii) order B (single-joint followed by multi-joint exercises) and iii) control group. Bench press was performed as multijoint while chest fly was performed as single-joint exercises. 1RM value for bench press and chest fly exercises were measured pre and post training intervention as an indicator for muscular strength adaptation. Repeated measure analysis of variances (ANOVA) was conducted to determine the effects of training intervention in each groups. The percentages of 1RM score changes during the post test was compared between all groups using one way ANOVA. Results showed that both order A and order B groups improved their 1RM value for both exercises. Bench press 1RM was found to be greater in order A group. Findings of this study suggested that performing a multi-joint exercise first promote greater gain for the multijoint exercise while performing single-joint exercise first lead to no differences in single joint exercise strength gain.

Stabilization training versus equilibrium training in karate athletes with deafness

The aim of this study is to compare the effect of stabilization and equilibrium training on hip muscle strength and balance performance of karate athletes with deafness. Twenty-seven athletes from the National Deaf Karate Team (18 males, nine females) with an average age of 24.53±3.62 (18–43) years were included in this study. The athletes were randomly assigned to either stabilization or equilibrium training group. Both training programs lasted 6 weeks with once per day and 5 days per week sessions. The assessment of muscle strength and balance performance was done before and after the training. The muscle strength and balance have improved in both training groups (P<0.05), but while there was no difference in the results of muscle strength between the groups (P>0.05), balance performance was better in the equilibrium training group (P<0.05). In conclusion, stabilization and equilibrium training have helped the karate athletes with deafness to improve their muscle strength and balance performance.

Effects of resistance training concentric velocity on older adults' functional capacity: A systematic review and meta-analysis of randomised trials

Reduced levels of functional capacity in older adults are related to lower quality of life, frailty, and sarcopenia, and can increase risk of falling, fractures and hospitalisation. Resistance training is an effective method to attenuate age-related functional declines. Based on the findings that muscle power and explosive strength are strongly associated with functional performance in older adults, it has been suggested that fast-intended-velocity resistance training may elicit greater improvements in functional capacity when compared to moderate-velocity resistance training. However, currently, there is no high-quality systematic review and meta-analysis supporting this assertion. The present study compared the magnitude of functional capacity improvements following resistance training performed with fast-intentional velocity versus moderate velocity. Pubmed, Scopus, and Web of Science databases were searched from inception to January 2019. The following eligibility criteria for selecting studies was adopted: Participants aged ≥60 years; resistance training based intervention for lower limbs performed solely with slow to moderate concentric velocity (≥2 s for each concentric phase) or solely with the intention of maximising velocity (i.e., as fast as possible); and at least one functional test for lower limbs, with pre- and post-intervention measurements. When studies employed multiple functional tests, a single (pooled) standardised mean difference was calculated and presented as combined functional capacity. In addition, functional tests were grouped accordingly to their specificity for the sub-groups meta-analyses. Fifteen studies were selected (high quality, n = 3; and pre-registered, n = 2). The results presented heterogeneity and small-studies publication bias, leading to a biased advantage for fast-intended-velocity resistance training (95%CI = 0.18, 0.65; I² = 45%). Short physical performance battery indicated an advantage for fast-intended-velocity resistance training (95%CI = 0.10, 0.94; I² = 0%). There was no difference for timed up and go (95%CI = -0.07, 0.94; I² = 48%), 30-s chair stand (95%CI = -0.24, 1.39; I² = 71%), 5-times chair stand (95%CI = -1.63, 1.27; I² = 57%) stair climb (95%CI = -1.89, 2.81; I² = 0%), short walk (95%CI = -0.99, 0.96; I² = 21%) and long walk (95%CI = -0.59, 1.00; I² = 0%). These results suggest that there is inconclusive evidence to support the superiority of fast-intended-velocity resistance training to improve functional capacity when compared to moderate-velocity resistance training. These results may have been influenced by the lack of high-quality and pre-registered studies, high heterogeneity, and small-studies publication bias. PROSPERO REGISTRATION NUMBER: CRD42019122251.

Effectiveness and optimal dosage of resistance training for chronic non-specific neck pain: a protocol for a systematic review with a qualitative synthesis and meta-analysis

INTRODUCTION

The prevalence of neck pain is increasing rapidly with a high percentage of patients going on to experience recurrent or chronic symptoms. The resulting pain and disability are commonly managed using a variety of treatments including exercise. Resistance training exercise aimed at the neck and shoulders is advocated to treat chronic non-specific neck pain (CNSNP), however the dosage of prescribed exercise varies considerably between studies. The aim of this study is to evaluate the effectiveness of resistance training in CNSNP and to determine an optimal dosage that should be prescribed in clinical practice.

METHODS AND ANALYSIS

A systematic review with qualitative synthesis and meta-analysis will be conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols. Cumulative Index to Nursing and Allied Health Literature, Excerpta Medica Database, Medical Literature Analysis and Retrieval System Online, PEDro, Zetoc, Index to Chiropractic Literature ChiroAcces, PubMed, grey literature sources and key journals will be searched. Randomised clinical trials investigating resistance training exercise in adults with CNSNP using outcome measures of pain and/or disability will be eligible for inclusion. Two reviewers will independently screen for eligibility, extract data and assess risk of bias (Cochrane risk of bias tool) with a third reviewer mediating in cases of disagreement. Data will be synthesised qualitatively to investigate intervention effectiveness and to determine the effect of exercise dosage on pain and disability. Meta-analysis using a random-effects model will be conducted where sufficient clinical homogeneity exists. The strength of the overall body of evidence will be assessed and reported using Grading of Recommendations Assessment, Development and Evaluation.

ETHICS AND DISSEMINATION

This study raises no ethical issues. Results will inform exercise prescription to improve management of CNSNP. Results will be published in a peer-reviewed journal and presented at conferences.

PROSPERO REGISTRATION NUMBER

CRD42018096187.